Regime transition and liquid retention mechanism of droplets impacting woven mesh

Under fixed liquid properties and wettability, droplet impact on a woven mesh is governed by competition between impact inertia and pore-throat capillary resistance. Droplet-to-opening size matching and local impact geometry are expected to redistribute liquid momentum among neighboring wires and openings, thereby determining retention or penetration.

Water droplets impacted a dry, single-layer stainless-steel woven (SSW) mesh. High-speed imaging resolved post-impact morphology, while Volume of Fluid (VOF) simulations, validated against the recorded sequences, quantified spreading, liquid retention, and the pressure and velocity fields over variations in Weber number (We), droplet diameter-to-opening ratio (λ), and impact location.

Retention (R), incomplete penetration (IP), and complete penetration (CP) were identified. Increasing We from 10 to 150 promoted pore-throat breakthrough and ligament growth, reducing the retention ratio (η_r) from 100% to 5.40%. At We = 50 and pore-center impact, η_r increased from 0.49% at λ = 1.00 to 37.52% at λ = 1.50, remained 36.71% at λ = 1.75, and decreased to 24.96% at λ = 2.00. Intermediate λ strengthened multi-wire capillary support, whereas larger λ increased liquid supply to the pore throats and intensified drainage. At We = 50 and λ = 1.50, moving impact from the pore center to the wire center and intersection reduced η_r from 37.52% to 8.40% and 4.40%, because the mesh skeleton redirected liquid toward additional drainage paths. Retention is therefore controlled by the coupled effects of impact inertia, droplet-opening matching, and local impact geometry.